The present invention relates to a method for lithographic printing and more particularly, it relates to a method for printing of books, magazines and the like, namely, so-called paginal publications.
Lithographic printing is performed by feeding both a coloring ink and water on the surface of a printing plate to have the coloring ink and the water selectively received by image area and non-image area, respectively and transfering the ink on the image area to a substrate such as a paper. Therefore, in order to obtain excellent printed matters, it is necessary that oleophilic activity of the image area and hydrophilc activity of the non-image area are both strong enough so that when water and ink are applied the image area can receive sufficient amount of ink while the non-image area can completely repel the ink.
As lithographic printing plates used at present, there are, for example, presensitized plates (PS plate) having a support of metals such as aluminum, printing plates obtained by electrophotography (e.g., electrofax), so-called master papers which comprise a paper base coated with a pigment together with a binder on the surface, photolithographic materials using silver salts disclosed in Japanese Patent Examined Publication (Kokoku) No. 30562/73, etc.
It is well known for printing of books, magazines, catalogues, newspapers which are to be bound to apply a plurality of printing plates to a printing machine. Light-sensitive lithographic printing plates for so-called direct plate making which have high sensitivity to various laser beams, such as silver salt type lithographic printing plates and electrophotographic printing plates have been increasingly demanded for use in printing of paginal publications because they can be used for plate making which utilizes computers. In the case of laser direct plate making methods, it is not only impossible to print many pages in one light-sensitive lithographic printing plate of large size according to the present output devices, but also difficult to print in a composition convenient for binding the pages into a book. Therefore, lithographic printing plates recorded thereon with information of respective pages must be separately made and combined. In the case of direct lithographic printing plates of process camera type, if the process camera is of small size, respective lithographic printing plates must also be combined. However, hitherto, printing of paginal publications by a large size printing machine by combining lithographic printing plates of small size has not been effected. The reason therefor is that when a plurality of lithographic printing plates are mounted and arranged in the direction of revolution of the master cylinder in such a manner that a tail edge of a first printing plate (the head edge of which is fixed to the master cylinder by a clamp or the like) and a head edge of a second printing plate and in some case, a tail edge of the second printing plate and a head edge of a third printing plate and so on are respectively connected, for example, by application of cellophane tape to backside thereof and printing of several thousands copies is carried out using these printing plates arranged in succession, there occur such severe problems as peeling-off of the second and the following printing plates, retention of ink between the printing plates and damage of blanket to make the subsequent printing impossible.
As a result of the inventors' intensive research in an attempt to solve the above problems, a printing method of paginal publications which satisfies the above demands and which has never been realized has been found.